Installation Notes TII Model 341 Protector (ATT-IS PEC 32918) for MERLIN Communications System In Range Out of Building (IROB) Station Installation By Trained Technician Only WARNING: Failure to follow these instructions could lead to personal injury and property damage. It will also void product warranties on all protected equipment.
1. General 1.01 This installation note covers the description and installation of the TII Model 341 Protector. The Model 341 is a protector designed to protect both the control unit and the station terminal of the MERLIN communications system from foreign voltages caused by lightning, power contact, or power induction. Two (2) Model 341 IROB protector units are installed whenever the station terminal is outside of the building but less than 1,000 feet from the MERLIN system control unit (Figure 1). Each Model 341 is orderable via Price Element Code (PEC) 32918. The installation must follow requirements as outlined in Article 800-2 of the National Electric Code Handbook, and AT&T Standard Practice #462-005-100. Other AT&T Practices that describe wiring for a non-fused protector are identified in Section 6. (Section 6 also identifies how to order all of these documents.) 1.02 The Model 341 Protector contains no field-serviceable components. If the protector must be replaced, the presence of hazardous voltages must be investigated before touching any exposed metallic parts. WARNING: Hazardous voltages may be present. Figure 1 Basic IROB Configuration
2. Description 2.01 The Model 341 contains both primary and secondary protection (Figure 2) mounted in a plastic housing with a hinged cover. Figure 2 IROB Internal Connections 2.02 The housing includes three (3) grommets for wire penetration, a No. 10 ground stud, and an eight-position modular jack. 2.03 A tie wrap must be inserted through a tab on the hinged cover for security. 2.04 The primary protection consists of four (4) TII 356L encapsulated, maximum-duty, three-electrode gas tube protector modules. 2.05 The solid state secondary surge protection is assembled on a printed wiring board within the Model 341.
3. Installation 3.01 Two (2) Model 341 Protectors are required for each IROB station terminal. One is placed where the cable from the control unit leaves the building. The second protector is placed where the cable enters the building in which the IROB station terminal is to be located. These units are intended for mounting in indoor locations only. 3.02 An approved ground is required for proper operation of the IROB protector. An approved ground is an acceptable power service ground, grounded building steel, concrete encased ground, or ring ground. The Model 341 Protector must be attached to an approved ground using No. 10 AWG copper wire or equivalent. The approved ground used for the Model 341 Protector must be bonded to the ground point for the ac power service using No. 6 AWG or equivalent. The wiring and grounding must follow requirements for a non-fused protector as outlined in Article 800-2 of the National Electrical Code Handbook, and AT&T Standard Practice #462-005-100. Other AT&T Practices that describe wiring for a non-fused protector are identified in Section 6. (Section 6 also identifies how to order all of these documents.) 3.03 Prior to operation of the MERLIN system, the integrity of the local telephone company-provided CO line protectors and grounding must be checked. Verify that the local telephone company has done the following: 1. Equipped the CO lines with protectors 2. Grounded the CO protector ground lugs to an approved ground 3. Bonded the CO protector ground to the ground point used for the ac power service Do not directly attach the Model 341 Protector to the ground lug of the protector block for the CO lines. 3.04 The exposed wire facility serving the station and control unit should enter the building within 10 feet of an approved ground such as the ac power ground. The National Electrical Code requires that the protector be located in, or immediately adjacent to, the structure or building served, and as close as practicable to the point at which the exposed conductors enter or attach. 3.05 Carefully unpack the protector, and select two or three of the five mounting holes. 3.06 Place the unit, with cover down, on some protected surface and remove the flashing from selected holes with the blade of a screwdriver. 3.07 With the door open, position the unit against the mounting surface, and mark the surface where the mounting holes are to be drilled.
3.08 Lay the unit carefully aside, and drill lead holes in the mounting surface as marked. If the surface is masonry, use the appropriate hardware. 3.09 Using No. 10 3/4" pan head screws, fasten the Model 341 Protector to the mounting surface. 4. Wiring 4.01 Before making any connections to the wire facilities, ground the protector by connecting a No. 10 AWG insulated solid copper wire to the ground post of the Model 341 Protector. This can be done by stripping off approximately one inch of insulation and wrapping the bare wire around the ground post under the washers and nut. 4.02 Using appropriate fasteners, run the ground wire as straight as possible to the nearest approved ground. See 3.02 for a description of the approved ground. 4.03 If a straight run is not possible, each bend must have a radius of at least nine inches. 4.04 Secure the end of the ground wire to the approved ground using a recommended ground clamp and tag. 4.05 The Voice 1, Voice 2, Control, and Power pairs may now be safely attached to the IROB terminals. (See Figure 2.) 4.06 Terminate the incoming pairs (22-26 AWG copper) on the type 66 quick-connect block located on the left side of the protector. The clips are arranged in descending order starting with the tip of the Voice 1 pair, followed by the ring of the Voice 1 pair, as shown in Figure 2. NOTE: If the incoming pairs are No. 20 AWG, 40 percent copper-clad fuse wire, terminate them directly on the black primary protector modules. Tip is left, and ring is right. 4.07 If out-of-building station cables are exposed to the possibility of power cross, there must be a fuse near the point of entrance. The fuse can be a 2-foot (minimum) length of 26 gauge wire, under a metal enclosure or part of a shielded cable. If the interbuilding wiring is a cable and the cable has a metallic shield, the shield must be bonded to the protector ground at both ends. 4.08 When the wiring of the Model 341 Protector is completed, the IROB station terminal modular cord or control unit modular cord may be plugged into the eight-position modular jack. Feed the modular plug and cord through the rectangular grommet at the bottom right-hand side of the unit, and insert the plug into the jack of the printed circuit board.
4.09 When all work is completed in the protector, close the cover by applying light pressure on the external tab until you hear the locking tabs snap shut. A security wire or tie wrap must be inserted into the oval hole. 5. Selection of an Approved Ground 5.01 The first choice for approved ground is some part of the power grounding system (Figure 3). The National Electrical Code requires that the telephone and power grounds be bonded with No. 6 AWG copper wire or equivalents and that an accessible means be provided at the electrical service for bonding other systems, such as telephone systems, to the power. The bonding point means may consist of an accessible metallic service entrance conduit, a power grounding conductor (see the note below), or a connector located on the exterior of the power service raceway or power service equipment (circuit breaker panel). NOTE: In some cases this may be a ground conductor from the interior of the circuit breaker panel which has been left accessible. The approved ground should be installed according to NEC 800-2 and AT&T Practice #462-005-100. Figure 3 Acceptable Grounding Connections to the Power Ground
5.02 Do not connect grounds to the following: Gas pipe Electric service branch circuit conduit Armor of BX cable Interior of any electrical box 6. References National Electrical Code Handbook, 1984, published by the National Fire Protection Association. AT&T Standard Practices. These are available from: Support Services AT&T Information Systems 99 Jefferson Road Room 2E09 Parsippany, New Jersey 07054 Telephone Number: 201-581-5685 Fax Number: 201-428-1878 AT&T Standard Practices include the following: 462-005-100, Station Protection and Grounds 876-300-100, Electrical Protection Stations and Customer Equipment 518-010-105, Key Telephone system. Ground and Special Protection Requirements 462-262-2xx (entire section of Practices), Wiring at Terminals 462-xxx-xxx (entire division), Drop and Block Wiring